Make gfx::Rect class operations consistently mutate the class they are called on.

webkit/plugins/npapi/webplugin_delegate_impl_gtk.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "webkit/plugins/npapi/webplugin_delegate_impl.h"
 
 #include <gtk/gtk.h>
 #include <gdk/gdkx.h>
 
 #include <string>
@@ skipping 337 matching lines @@
   // |       |       H  plugin                      |                  H
   // |       +-------#------------------------------+                  H
   // |               H                                                 H
   // |               H                  "apparent" window              H
   // +---------------#=================================================#
   // X = "real" origin
   // O = "apparent" origin
   // "real" means as seen by Chrome
   // "apparent" means as seen by the plugin.
 
-  gfx::Rect draw_rect = window_rect_.Intersect(damage_rect);
+  gfx::Rect draw_rect = window_rect_;
+  draw_rect.Intersect(damage_rect);
 
   // clip_rect_ is relative to the plugin
   gfx::Rect clip_rect_window = clip_rect_;
   clip_rect_window.Offset(window_rect_.x(), window_rect_.y());
-  draw_rect = draw_rect.Intersect(clip_rect_window);
+  draw_rect.Intersect(clip_rect_window);
 
   // These offsets represent by how much the view is shifted to accomodate
   // Flash (the coordinates of X relative to O in the diagram above).
   int offset_x = 0;
   int offset_y = 0;
   if (quirks_ & PLUGIN_QUIRK_WINDOWLESS_OFFSET_WINDOW_TO_DRAW) {
     offset_x = -draw_rect.x();
     offset_y = -draw_rect.y();
     window_.clipRect.top = 0;
     window_.clipRect.left = 0;
@@ skipping 372 matching lines @@
     // as someone might be setting the cursor in the main process as well.
     *cursor = current_windowless_cursor_;
   }
 #endif
 
   return ret;
 }
 
 }  // namespace npapi
 }  // namespace webkit